(function() {
  'use strict';

  function sprintf() {
    // http://kevin.vanzonneveld.net
    // +   original by: Ash Searle (http://hexmen.com/blog/)
    // + namespaced by: Michael White (http://getsprink.com)
    // +    tweaked by: Jack
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +      input by: Paulo Freitas
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +      input by: Brett Zamir (http://brett-zamir.me)
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   improved by: Dj
    // +   improved by: Allidylls
    // *     example 1: sprintf("%01.2f", 123.1);
    // *     returns 1: 123.10
    // *     example 2: sprintf("[%10s]", 'monkey');
    // *     returns 2: '[    monkey]'
    // *     example 3: sprintf("[%'#10s]", 'monkey');
    // *     returns 3: '[####monkey]'
    // *     example 4: sprintf("%d", 123456789012345);
    // *     returns 4: '123456789012345'
    var regex = /%%|%(\d+\$)?([-+\'#0 ]*)(\*\d+\$|\*|\d+)?(\.(\*\d+\$|\*|\d+))?([scboxXuideEfFgG])/g;
    var a = arguments,
      i = 0,
      format = a[i++];

    // pad()
    var pad = function(str, len, chr, leftJustify) {
      if (!chr) {
        chr = ' ';
      }
      var padding = (str.length >= len) ? '' : Array(1 + len - str.length >>> 0).join(chr);
      return leftJustify ? str + padding : padding + str;
    };

    // justify()
    var justify = function(value, prefix, leftJustify, minWidth, zeroPad, customPadChar) {
      var diff = minWidth - value.length;
      if (diff > 0) {
        if (leftJustify || !zeroPad) {
          value = pad(value, minWidth, customPadChar, leftJustify);
        } else {
          value = value.slice(0, prefix.length) + pad('', diff, '0', true) + value.slice(prefix.length);
        }
      }
      return value;
    };

    // formatBaseX()
    var formatBaseX = function(value, base, prefix, leftJustify, minWidth, precision, zeroPad) {
      // Note: casts negative numbers to positive ones
      var number = value >>> 0;
      prefix = prefix && number && {
        '2': '0b',
        '8': '0',
        '16': '0x'
      }[base] || '';
      value = prefix + pad(number.toString(base), precision || 0, '0', false);
      return justify(value, prefix, leftJustify, minWidth, zeroPad);
    };

    // formatString()
    var formatString = function(value, leftJustify, minWidth, precision, zeroPad, customPadChar) {
      if (precision != null) {
        value = value.slice(0, precision);
      }
      return justify(value, '', leftJustify, minWidth, zeroPad, customPadChar);
    };

    // doFormat()
    var doFormat = function(substring, valueIndex, flags, minWidth, _, precision, type) {
      var number;
      var prefix;
      var method;
      var textTransform;
      var value;

      if (substring === '%%') {
        return '%';
      }

      // parse flags
      var leftJustify = false,
        positivePrefix = '',
        zeroPad = false,
        prefixBaseX = false,
        customPadChar = ' ';
      var flagsl = flags.length;
      for (var j = 0; flags && j < flagsl; j++) {
        switch (flags.charAt(j)) {
          case ' ':
            positivePrefix = ' ';
            break;
          case '+':
            positivePrefix = '+';
            break;
          case '-':
            leftJustify = true;
            break;
          case "'":
            customPadChar = flags.charAt(j + 1);
            break;
          case '0':
            zeroPad = true;
            break;
          case '#':
            prefixBaseX = true;
            break;
        }
      }

      // parameters may be null, undefined, empty-string or real valued
      // we want to ignore null, undefined and empty-string values
      if (!minWidth) {
        minWidth = 0;
      } else if (minWidth === '*') {
        minWidth = +a[i++];
      } else if (minWidth.charAt(0) == '*') {
        minWidth = +a[minWidth.slice(1, -1)];
      } else {
        minWidth = +minWidth;
      }

      // Note: undocumented perl feature:
      if (minWidth < 0) {
        minWidth = -minWidth;
        leftJustify = true;
      }

      if (!isFinite(minWidth)) {
        throw new Error('sprintf: (minimum-)width must be finite');
      }

      if (!precision) {
        precision = 'fFeE'.indexOf(type) > -1 ? 6 : (type === 'd') ? 0 : undefined;
      } else if (precision === '*') {
        precision = +a[i++];
      } else if (precision.charAt(0) == '*') {
        precision = +a[precision.slice(1, -1)];
      } else {
        precision = +precision;
      }

      // grab value using valueIndex if required?
      value = valueIndex ? a[valueIndex.slice(0, -1)] : a[i++];

      switch (type) {
        case 's':
          return formatString(String(value), leftJustify, minWidth, precision, zeroPad, customPadChar);
        case 'c':
          return formatString(String.fromCharCode(+value), leftJustify, minWidth, precision, zeroPad);
        case 'b':
          return formatBaseX(value, 2, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
        case 'o':
          return formatBaseX(value, 8, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
        case 'x':
          return formatBaseX(value, 16, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
        case 'X':
          return formatBaseX(value, 16, prefixBaseX, leftJustify, minWidth, precision, zeroPad).toUpperCase();
        case 'u':
          return formatBaseX(value, 10, prefixBaseX, leftJustify, minWidth, precision, zeroPad);
        case 'i':
        case 'd':
          number = +value || 0;
          number = Math.round(number - number % 1); // Plain Math.round doesn't just truncate
          prefix = number < 0 ? '-' : positivePrefix;
          value = prefix + pad(String(Math.abs(number)), precision, '0', false);
          return justify(value, prefix, leftJustify, minWidth, zeroPad);
        case 'e':
        case 'E':
        case 'f':
          // Should handle locales (as per setlocale)
        case 'F':
        case 'g':
        case 'G':
          number = +value;
          prefix = number < 0 ? '-' : positivePrefix;
          method = ['toExponential', 'toFixed', 'toPrecision']['efg'.indexOf(type.toLowerCase())];
          textTransform = ['toString', 'toUpperCase']['eEfFgG'.indexOf(type) % 2];
          value = prefix + Math.abs(number)[method](precision);
          return justify(value, prefix, leftJustify, minWidth, zeroPad)[textTransform]();
        default:
          return substring;
      }
    };

    return format.replace(regex, doFormat);
  }

  module.exports = sprintf;
})();